Pass Multiline Prompts to Claude Code with Shell HEREDOCs

When you're scripting with claude --print, trying to cram a multi-point prompt into a single quoted string gets ugly fast. Shell HEREDOCs give you clean, readable multi-line prompts with no escaping.

claude --print << 'EOF'
Review the following code for:
1. Security vulnerabilities
2. Performance bottlenecks
3. Missing error handling

Respond with a bullet list for each category.
EOF

Single-quoting the delimiter ('EOF') prevents the shell from expanding variables inside the HEREDOC — useful when your prompt contains dollar signs or backticks. Drop the quotes when you want variable interpolation:

FILE="src/auth/middleware.ts"
CONTEXT="This is a financial application handling PII data."

claude --print << EOF
Context: $CONTEXT

Review $(basename $FILE) for security issues only.
Be brief — one sentence per issue.

$(cat $FILE)
EOF

This pattern works well in Makefiles too:

review:
	@claude --print << 'EOF'
	Summarise what changed in the last 5 commits and flag anything risky.
	$(shell git log --oneline -5)
	EOF

HEREDOCs make Claude automation scripts dramatically more readable than escaped single-liners.